1. Field of the Invention
This invention relates to the measurement of position and orientation of an object using one or more photometric sensors attached to the object and a special illuminator.
2. Description of the Prior Art
For various applications such as inspection of machined parts or control of a robot manipulator, it is desired to know the position and orientation of an object as it is moved through space. Whether the object is a contact probe for automatic inspection, a robot assembly gripper or the like, the data requirements are similar. In current technology, the object coordinates are found using encoders built into precision hardware such as granite blocks on air bearings or arm extenders which connect the object to a reference base. In order to achieve an accurate measurement of the object coordinates, the connecting hardware must be stiff and heavy, which results in slow and expensive apparatus.
To overcome these problems optical systems have been developed, as described in U.S. Pat. Nos. 3,662,180, 704,070 and 3,799,675. The first two of these patents teach direction determining systems in which a simple cylindrical grating or one cylindrical grating which moves with respect to a second cylindrical grating surrounds a light source. This leads to inaccuracies. The above-cited patents relate to angular position determining systems. U.S. Pat. Nos. 4,231,662, 4,176,276 and 3,586,665 relate to linear position determining systems.